*: remove session variable statuses

plan/plans/show.go

@@ -468,23 +468,7 @@ func (s *ShowPlan) fetchShowVariables(ctx context.Context) error {
 	return nil
 }
 
-func getSessionStatusVar(ctx context.Context, sessionVars *variable.SessionVars,
-	name string, globalVal *variable.StatusVal) (string, error) {
-	sv, ok := sessionVars.StatusVars[name]
-	if ok {
-		return sv, nil
-	}
-
-	gv, err := types.ToString(globalVal.Value)
-	if err != nil {
-		return "", errors.Trace(err)
-	}
-
-	return gv, nil
-}
-
 func (s *ShowPlan) fetchShowStatus(ctx context.Context) error {
-	sessionVars := variable.GetSessionVars(ctx)
 	m := map[interface{}]interface{}{}
 
 	statusVars, err := variable.GetStatusVars()
@@ -514,12 +498,7 @@ func (s *ShowPlan) fetchShowStatus(ctx context.Context) error {
 		}
 
 		var value string
-		if !s.GlobalScope {
-			value, err = getSessionStatusVar(ctx, sessionVars, status, v)
-			if err != nil {
-				return errors.Trace(err)
-			}
-		} else if v.Scope != variable.ScopeSession {
+		if !s.GlobalScope || (s.GlobalScope && v.Scope != variable.ScopeSession) {
 			value, err = types.ToString(v.Value)
 			if err != nil {
 				return errors.Trace(err)

plan/plans/show_test.go

@@ -228,7 +228,6 @@ func (p *testShowSuit) TestShowStatusVariables(c *C) {
 	c.Assert(fls[0].Col.Tp, Equals, mysql.TypeVarchar)
 	c.Assert(fls[1].Col.Tp, Equals, mysql.TypeVarchar)
 
-	sessionVars := variable.GetSessionVars(p.ctx)
 	ret := map[string]string{}
 	rset := rsets.Recordset{
 		Ctx:  p.ctx,
@@ -244,59 +243,36 @@ func (p *testShowSuit) TestShowStatusVariables(c *C) {
 	c.Assert(v, DeepEquals, testStatusValBothScope)
 	pln.Close()
 
-	sessionVars.StatusVars[testStatusBothScopes] = "changed_val"
-	pln.GlobalScope = false
-	rset.Do(func(data []interface{}) (bool, error) {
-		ret[data[0].(string)] = data[1].(string)
-		return true, nil
-	})
-	c.Assert(ret, HasLen, 1)
-	v, ok = ret[testStatusBothScopes]
-	c.Assert(ok, IsTrue)
-	c.Assert(v, DeepEquals, "changed_val")
-	pln.Close()
-
+	pln.GlobalScope = true
 	pln.Pattern = &expression.PatternLike{
 		Pattern: &expression.Value{
 			Val: testStatusSessionScope,
 		},
 	}
-	sessionVars.StatusVars[testStatusSessionScope] = "on"
-	pln.GlobalScope = true
 	ret = map[string]string{}
 	rset.Do(func(data []interface{}) (bool, error) {
 		ret[data[0].(string)] = data[1].(string)
 		return true, nil
 	})
 	c.Assert(ret, HasLen, 0)
-
-	pln.GlobalScope = false
-	rset.Do(func(data []interface{}) (bool, error) {
-		ret[data[0].(string)] = data[1].(string)
-		return true, nil
-	})
-	c.Assert(ret, HasLen, 1)
-	v, ok = ret[testStatusSessionScope]
-	c.Assert(ok, IsTrue)
-	c.Assert(v, Equals, "on")
 	pln.Close()
 
 	pln.Pattern = nil
+	pln.GlobalScope = false
 	pln.Where = &expression.BinaryOperation{
 		L:  &expression.Ident{CIStr: model.NewCIStr("Variable_name")},
 		R:  expression.Value{Val: testStatusBothScopes},
 		Op: opcode.EQ,
 	}
 	ret = map[string]string{}
-	sessionVars.StatusVars[testStatusBothScopes] = "0"
 	rset.Do(func(data []interface{}) (bool, error) {
 		ret[data[0].(string)] = data[1].(string)
 		return true, nil
 	})
 	c.Assert(ret, HasLen, 1)
 	v, ok = ret[testStatusBothScopes]
 	c.Assert(ok, IsTrue)
-	c.Assert(v, Equals, "0")
+	c.Assert(v, Equals, testStatusValBothScope)
 }
 
 func (p *testShowSuit) TestIssue540(c *C) {

sessionctx/variable/session.go

@@ -23,8 +23,6 @@ type SessionVars struct {
 	Users map[string]string
 	// system variables
 	Systems map[string]string
-	// status variables
-	StatusVars map[string]string
 	// prepared statement
 	PreparedStmts map[string]interface{}
 	// prepared statement auto increment id
@@ -60,7 +58,6 @@ func BindSessionVars(ctx context.Context) {
 	v := &SessionVars{
 		Users:         make(map[string]string),
 		Systems:       make(map[string]string),
-		StatusVars:    make(map[string]string),
 		PreparedStmts: make(map[string]interface{}),
 	}